Following the linguist David Chrystal, rhetoric may be defined simply as, “the study of effective or persuasive speaking and writing, especially as practiced in public oratory” (2003). Rhetoric attempts to persuade others to accept a particular viewpoint and, thereby, build consensus. It assumes a discussion between competing perspectives, and it relies on argument and evidence -- as well as appeals to authority, emotion, or logic -- to convince. While rhetoric is sometimes derided as deceptive or disingenuous, it might be more generously seen as the art of making the right appeal to the right audience at the right moment.
Aristotle: “[Rhetoric]” is the faculty of discovering in any particular case all of the available means of persuasion.”
St. Augustine: “Rhetoric is the art of expressing clearly, ornately (where necessary), persuasively, and fully the truths which thought has discovered acutely.”
Bacon: “Rhetoric is the application of reason to imagination for the better moving of the will.”
I.A. Richards: “Rhetoric is the study of misunderstandings and their remedies.”
Bitzer: “Rhetoric is a mode of altering reality, not by the direct application of energy to objects, but by the creation of discourse which changes reality through the mediation of thought and action.”
Derrida: “There is no society without rhetoric.” From Wayne Booth, The Rhetoric of Rhetoric, 2004
Academic reference sources, like subject-specific encyclopedias, dictionaries, and handbooks, can provide short-form overviews of a field -- a quick way of "getting our teeth around" an issue or area of inquiry. Here are a few print and digital resources available from Memorial Library that might help orient us.
doxa: public opinion, commonly held belief
ethos: appeal to character or authority
kairos: opportune moment, the right appeal to the right audience
lexis: style and delivery
logos: appeal to logic and reason
metalepsis: referring to a one thing by reference to another, often for comical effect
pathos: appeal to emotion
stasis: key point at issue in a debate
A thorough overview of key terms and concepts in rhetoric is available at Silva Rhetroricae, sponsored by Brigham Young University.